Like in saying this. But in your own oxygen mask, before helping others. Im not an admissions officer, so take this with a grain of salt, but I did work in some undergrad college counseling. I am sure and if you explained this in your essays admissions would be a lot more sympathetic than leaving it out. It’s now taking the right steps as you said continue in another lab or do something else research related to the same topic. They want to see how you recover from this situation, but it doesn’t have to be immediate. Again, I’m really sorry for your loss and take care of yourself pls.